Power hammer



Aug. 6, 1940, N A E ON 2,210,020

- POWER HAMMER Filed Jan. 2:, 1939 ATTO-RNEY.

Patented Aug. 6, 1940 POWER HAMMER Norman Anderson, Duluth, Minn.

' Application January 23 I 3 Claims.

' .by compressed air in the restoration and repair of light sheet metal such as encountered indamaged or dentedautomobile fenders, bodies, or the like. a In the use of similar instrumentalities of this character in such work one objection'that has been encountered with the ordinary air or percussion hammer is the fact that the thrust of the hammer head from the surrounding anvil is not amenable to a predetermined thrust or projection beyond the anvil, and this frequently results in overstressing of the metal in the wrong direction,

especially when but light blows are essential in bringing the surface of the metal back to normalcy. To overcome such objection is the principal object of the instant invention.

Another object is that of providing means whereby the limit of each stroke is at all times positive. I

Other objects and advantages of the invention will appear in the following description thereof.

Referring now to the accompanying drawing, forming part of this application, and wherein like reference characters indicate like parts:

Figure 1 is a somewhat enlarged diagrammatic sectional view through an air hammer embodying the invention.

Figure 2 is a broken elevation of a slightly modified form in respect to Figure 1 especially in that the body portion of the hammer is slightly. rotated.

In the drawing l represents the body portion of the hammer which is of metal and preferably cylindrical in form and provided with end covering portions 2 and 3 which may be fixed to the body portion in any desired manner as by suitable tap bolts indicated at 4, the same being common. in the construction of such tools.

Within the body portion I are formed two parallel cylindrical chambers 5 and 6, their respective positions as here shown being simply for convenience in the comprehension of their cooperative relation and obviously may be arranged differently without departing from the invention.

Within the chamber 6 is located the elongated reciprocal hammer operating piston I, it having formed integral therewith the reduced hammer portion 8 which extends through the end 3 of the body portion and administers the blow to the work being engaged. Thatportion, of the end member 3 through which the hammer end of the piston I extends is materially elongated and of sleeve-like construction, as indicated at 9, it being externally screw threaded for the reception 1939, Serial No. 252,271 (01. 1215-13) of first thelock nut I and second the stepped anvil I I. This latter member is here referred to as an anvil as it is the member which is held against the workbeing operated upon, and is cylindrical in form and also internally screw threaded as shown for application to the sleeve 9. The tapered'terminal end I2 of the hammer is projectable from the end of the anvil which may be adjusted longitudinally of the sleeve to any desired position and there held by adjustment of the lock nut I 0 upon the sleeve.

It is to be understood that the length of stroke of the hammer piston is at all times the same though with varying degrees of effectiveness in relation to the pressure of fluid applied, however, due to the previously described adjustable "feature of the anvil, the distance that the end of the hammer may protrude therebeyond may be readily predetermined, so that when but a slight variation in the surface to be operated upon is required, the extent of protrusion of the hammer beyond the anvil may be delicately adjusted accordingly, and that irrespective of the fixed stroke of the hammer, resulting in a marked expedition of the desired results in such delicate work.

For accomplishing the regular and uniform stroke of the hammer piston, I have provided within the chamber 5, the cylindrical piston like valve l3, which is operated back and forth in unison with the hammer piston by action of the power fluid. To this end I have illustrated the intake passageway I4 extending longitudinally of the body portion 1 and communicating as by the branch passageway l and angular port 25 through the chamber 5 and passageway Hi to the driving end of the hammer piston I in the chamber 6, while at the opposite end a branch passageway I1 is shown as communicating through the chamber 5 and connecting with the passageway l8 to the opposite end of the hammer piston I within the chamber 6. Exhaust passageways are indicated at I9 and 20, they also extending from the exterior of the body portion through the chamber 5 to the chamber 6 and at either end thereof, they diflering somewhat in their entrance to the chamber 6 in that the location of the entrance of the passageway I9 is spaced some considerable distance from the rear wall or head 2 of the body portion, this being for the purpose of providing air cushioning efi'ect resulting when the piston I is concluding its backward stroke, while the entrance to the exhaust passageway 20 in the opposite or forward end of the chamber 6 is immediately adjacent the forward end of the chamher 6 so that no cushioning of the forward stroke of the piston 1 occurs other than that provided by a suitable form of slightly resilient washer or gasket indicated at II.

The other two control passageways 22 and 23 intermediate of the chambers 5 and 6 terminate within the former chamber at its extreme ends, while their entrance into the chamber 6 are spaced equally distant from the ends thereof and in proper relation to the stroke of the piston I so that when said piston, for example, reaches substantially the limit of its forward stroke for engagement with the limiting washer 2| the passageway 22 will be opened in respect to the chamber 6 and instantly permit the power fluid to pass therethrough to the rear end of the valve l3 and force it forwardly to the position shown in dotted lines, thus opening the exhaust passageway it directly through the chamber 5, past the rear end of the valve it, simultaneously with bringing the annular port 2 5 about the valve it into registration with the passageways li-iB communicating with the forward end of the chamber 6 and head of the piston l for returning the latter to its original position. At this latter time the passageway 23 will be opened for admitting the power fluid again to the forward end of the chamber 5 and returning the valve 13 to its former position as illustrated when again the annular port 25 will register with the branch passageways l5l6 ready for the next forward stroke of the piston l, thus providing a simple and practical application of the power fluid together with. the novel feature of the piston I being air cushioned upon its backward stroke and with but little if any cushioning whatever upon the termination of the forward stroke, thus abnormally energizing the anvil at each stroke, which is also deemed novel in such a hammer.

As before stated, the layout of power fluid passageways is only diagrammatic for convenience in a better comprehension of same, but their termination in the chambers for accomplishing the results described is essential.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

l. A power hammer of the type described having a housing, a sleeve like extension'from said housing, a reciprocal striking element within said housing and projecting from said sleeve, selectively adjustable gaging means surrounding the ends of said striking element and sleeve whereby to predetermine the projection of said element beyond said gaging means at each blow.

2. A power hammer of the type described having a housing, a sleeve-like extension from said housing, a reciprocable striking element within said housing and projecting from said sleeve, selectively adjustable gaging means surrounding the ends of said striking element and sleeve whereby to predetermine the projection of said element beyond said gaging means at each blow, said gaging means forming a bearing for the outer end of said striking element.

3. A power hammer of the type described having a housing, a sleeve-like extension from said housing, a reciprocable striking element within said housing and projecting from said sleeve, selectively adjustable gaging means screwthreadedly mounted upon said extension and forming a bearing for the outer end of said striking element, and a lock nut screw threadedly mounted on said extension for holding said gaging means in any relative position on said sleeve.

NORMAN ANDERSON.

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